whatsnew.txt

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New features in Version 23.8 of prime95.exe
-------------------------------------------

1)  A communication bug, Primenet Error 1, was fixed in the case where
    proxy software inserted the text "NetAnts: MaxConnection=1" in the HTML
    response from the Primenet server.
2)  Fixed memory allocation bug in torture test when using 926MB of memory
    on the 20K FFT size.
3)  The program will now try both full and a relative URL in trying to
    contact the PrimeNet server.  Some rare setups only work with full URLs
    and some only work with relative URLs.  The small downside is there might
    be an increase in network traffic when the server is down.  If this is
    a concern you can use the UseFullURL option described in undoc.txt.    

New features in Version 23.7 of prime95.exe
-------------------------------------------

1)  A bug was fixed where the torture test used more virtual memory than
    necessary, sometimes resulting in an "Out of memory" error.

New features in Version 23.6 of prime95.exe
-------------------------------------------

1)  Several changes have been made to the torture test.
    a) Machines faster than 1 GHz will use new test data that runs a lot more
       iterations.  This will reduce time spent in initialization code,
       hopefully increasing stress on the CPU.
    b) The torture test stops after 100 ILLEGAL SUMOUT errors.
    c) There are now 3 flavors of torture testing.  One that operates on small
       FFTs only, theoretically maximizing FPU stress.  One that operates 
       in place on large FFTs only, maximizing heat and power drain.  One that
       runs a blend of tests using lots of memory, possibly catching errors
       that might only occur at a specific memory address.

New features in Version 23.5 of prime95.exe
-------------------------------------------

1)  Four changes have been made after GIMPS' first false positive report
    in 7 1/2 years of operation.
    a) The program now returns the number of errors that occurred when the
       result is prime.  A non-zero value will make us more suspect of the
       reported prime.
    b) The save files will not be deleted.  The user can then email these to
       me and we can rerun the last 30 minutes of the LL test.  It is hard
       to imagine a second false positive report in this mini LL run.
    c) The shift counter is now checked every iteration.  If this variable
       AND the FFT data was corrupted, then and endless loop of LL iterations
       generating zero is possible - resulting in a false prime report.
    d) Every iteration the FFT data is checked to see if the data has been
       zeroed.
    e) The is-this-a-prime check now makes sure the FFT data is not NaN.
       NaN stands for not a number and means the data is corrupt.  The
       previous version checked for zero and my C compiler returns TRUE for
       the test NaN == 0.0!
2)  I restored the old behavior sending relative URLs.  Some users had trouble
    with this feature introduced in 23.4.  So, UseFullURL=0 is now the default.
3)  Some prefetching improvements were made for the Athlon, Pentium 3, and 
    Celeron 2 processors.  You can expect speed improvements between 3%
    and 10% for most FFT sizes.  Warning: the new code is slower for Durons
    and Celeron's with small L2 caches for FFT sizes 1024K and above.

New features in Version 23.4 of prime95.exe
-------------------------------------------

1)  Further performance improvements in the SSE2 FFT code.  I've tried to
    do more work while data is in the L1 data cache.
2)  The program should now work with a "redirected proxy server".  This was
    done by sending full URLs in Primenet requests.  While I don't anticipate
    any problems, the old relative URL functionality can be had by setting
    UseFullURL=0 in primenet.ini.
3)  A bug in the assembly language add and subtract routines was fixed.  The
    bug could affect ECM on exponents just below
    MAXIMUM_EXPONENT_FOR_FFTLEN - FFTLEN/2.

New features in Version 23.3 of prime95.exe
-------------------------------------------

1)  Further performance improvements in the SSE2 code for FFTs larger than
    640K.  You should see about a 4% improvement in LL tests on a P4.  However,
    FFTs between 40K and 512K might be a tiny bit slower.
2)  Stage 2 of P-1 factoring has been recoded for more speed.  WARNING: when
    continuing from a save file created in stage 2 by a previous prime95
    version, this version will restart stage 2 from the beginning.  ALSO:
    the stage 2 P-1 save file format has changed - in dual boot scenarios
    you must upgrade mprime and prime95 at the same time.

New features in Version 23.2 of prime95.exe
-------------------------------------------

1)  Further performance improvements in the SSE2 code.  You can expect about
    a 5% improvement in LL tests on a P4.

New features in Version 23.1 of prime95.exe
-------------------------------------------

1)  Big SSE2 FFTs now take the L2 cache size into account.  P4 Celeron (128KB
    L2 cache) is faster for FFTs between 512K and 2M.  P4 Northwood (512KB
    L2 cache) is faster for FFTs larger than 1M.
2)  Benchmark no longer times 256K and 320K FFTs, but does time 2048K FFT.
3)  Support for torture testing FFT sizes from 1280K to 4096K added.
4)  A 900 MHz P-III is now required to get first time LL tests by default.
5)  Slightly faster SSE2 FFTs for lengths of 5*2^N and 7*2^N (e.g. 640K, 896K).

New features in Version 22.13 of prime95.exe
--------------------------------------------

1)  A P-1 and ECM QA suite was implemented.  A bug in ECM for exponents
    below 172,700 and near the limit of an FFT size and using SSE2 code
    was fixed.

New features in Version 22.12 of prime95.exe
--------------------------------------------

1)  A bug was fixed that caused some factors to be missed in stage 2 of P-1
    when the available memory did not let the program allocate 12 temporary
    variables.  If testing a number in the 16 millions using an FFT size of
    768K, then each temporary takes 768K * 8 bytes or 6MB.  If your memory
    setting was less than 72MB (6MB * 12 temporaries) then you were affected
    by the bug.  Actual the program allocates some fixed tables so anything
    less than about 75MB triggered the bug.

New features in Version 22.11 of prime95.exe
--------------------------------------------

1)  A bug that caused factors to be missed in the last stage of P-1 and ECM
    factoring was fixed.  The bug was introduced in executables built after
    Sept. 28, 2002.

New features in Version 22.10 of prime95.exe
--------------------------------------------

1)  When running a double-check assignment the preferred trial factoring
    depth is reduced one bit.  This is done because finding a factor will
    save one LL test instead of the usual two LL tests.
2)  On a Windows NT/2000/XP system, if prime95 is run by a user without
    administrator privileges then prime95 cannot install itself as a service.
    Thus, the Start at Bootup option will set prime95 to run at login time
    rather than bootup time.
3)  A crash bug when selecting "Start at Bootup" on Windows NT3 and Windows NT4
    systems was fixed.
4)  Bug in starting more than one prime95 as NT services on multi-processor
    machines was fixed.

New features in Version 22.9 of prime95.exe
-------------------------------------------

1)  Error rate for a clean run is now estimated at 1.8% raising your chances
    of finding a Mersenne prime while double-checking.
2)  You can now stop and continue testing from the system tray menu.
3)  You can now pause prime95 when another program starts running.  See the
    PauseWhileRunning option in undoc.txt.
4)  Fixed bug introduced in 22.8 where No Icon did not work if Start at Bootup
    was also specified in Windows 98.
5)  A bug in unscrambling the proxy server password in primenet.ini was fixed.

New features in Version 22.8 of prime95.exe
-------------------------------------------

1)  Soft FFT crossovers have been implemented.  If you test an exponent that
    is within 0.2% of the old hard FFT crossover point, then 1000 test
    iterations are run to determine if the smaller or larger FFT is
    appropriate for the exponent.  Although not recommended, you can adjust
    prime95's behavior to be more aggressive using the SoftCrossover and
    SoftCrossoverAdjust features discussed in undoc.txt.
2)  To better stress main memory, the torture test will now use up to the
    amount of memory specified in the Options/CPU dialog box.
3)  Iterations with roundoff checking are a little faster for non-SSE2 CPUs.

New features in Version 22.7 of prime95.exe
-------------------------------------------

1)  Trial factoring above 2^64 on a P4 now uses the SSE2 instructions.
    This is more than four times as fast as the previous version.
2)  Old Advanced/Factoring save files are not compatible with this version.
    They are named p0000000 and should be deleted.  This should not be a
    problem as no one should be using this obsolete and unsupported feature.
3)  Four more x87 FFT crossover changes as suggested by Brian Beesley's
    research.
4)  You can now change the NT/2000/XP service name and service display name.
    See undoc.txt for details.
5)  Bug where found factors were silently truncated to 200 digits was fixed.

New features in Version 22.6 of prime95.exe
-------------------------------------------

1)  The Start At Bootup option now runs prime95 as a Windows NT/2000/XP
    service!!  Normally Windows NT/2000/XP will not run GUI programs as
    services, but several tricks have allowed us to get this working
    almost flawlessly.
2)  To reduce spurious error reports on x86 LL tests near the crossover
    points, the program now allows roundoff errors less than 0.40625
    rather than less than 0.4.

New features in Version 22.5 of prime95.exe
-------------------------------------------

1)  A bug in P4 roundoff error recovery was fixed.  Bug was present in
    version 22 executables dated between May 22 and June 18.
2)  Prime95 now properly detects if the program is running by another
    logged in Windows XP user.
3)  When Tray Icon or Hide Icon is set, the "X" in the upper right corner
    no longer closes prime95 rather it minimizes it.  Also right clicking
    the tray icon now brings up a popup menu.
4)  Changed the way prime95 shuts down.  Logoff in WinXP used to hang.

New features in Version 22.4 of prime95.exe
-------------------------------------------

1)  A little more tweaking of the FFT crossovers.
2)  A GCD hang bug was fixed in case where there were a large number of
    entries in the lowm.txt file.  Another GCD bug affecting ECM on F18
    was fixed.

New features in Version 22.3 of prime95.exe
-------------------------------------------

1)  Given more data, the roundoff error checking is now done on every
    iteration for exponents within 0.5% of the maximum that can be tested
    by the current FFT length.  If a roundoff error above 0.4 occurs,
    then the iteration is now repeated without any change to the shift count.
    It now takes a roundoff error greater than 0.6 to corrupt the results.
2)  Many of the FFT ranges have changed.  Version 21 was too aggressive
    in choosing FFT sizes for the P4.  The new handling of roundoff
    errors above 0.4 lets us be more aggressive with the non-P4 code.
3)  Result lines are now WYn rather than WXn.
4)  A crash bug affecting P-1 and ECM using the 2^N+1 option for large N was
    fixed.
5)  A rare memory corruption and possible crash bug in the GCD code was
    fixed.
6)  The -t command line argument will run the torture test.
7)  To reduce wild fluctuations in the RollingAverage, it will be updated
    roughly twice per day.

New features in Version 22.2 of prime95.exe
-------------------------------------------

1)  Factoring assignments go to machines slower than a 233 MHz Pentium.
    Double-checks are assigned machines slower than a 500 MHz P-III.
2)  The speed of the GCD has been improved.
3)  Some of the P4 FFT ranges have changed.  Version 21 was too aggresive
    in choosing FFT sizes for the P4.
4)  Roundoff error checking is now done on every iteration for exponents
    within 2% of the maximum that can be tested by the current FFT length.
    See undoc.txt for ways to disable this new feature.
5)  The previous version would get into an infinite loop if a repeatable
    roundoff error larger than 0.48 was discovered.  Now if a repeatable
    roundoff error greater than 0.45 is found, then the iteration is
    repeated after shifting the FFT data.

New features in Version 22.1 of prime95.exe
-------------------------------------------

1)  Some bugs in error handling when communicating with the server have
    been fixed.
2)  Communicating with the server by RPC is no longer supported.  The
    HTTPNET.DLL and RPCNET.DLL have been deleted.  Only "Basic" Proxy server
    authentication is supported.  Version 21 may have supported MS Proxy
    Server 2.0's NTLM (NT Lan Manager) challenge/response authentication.
3)  The program now uses a high resolution timer rather than the RDTSC
    instruction to time events.  This should help the program display accurate
    timings on laptops with SpeedStep or desktops that can hibernate.  You can
    force the program to use the old RDTSC timing method with the RdtscTiming
    option described in undoc.txt.
4)  The program uses a updated algorithm to automatically detect CPU type and
    speed.  The Options/CPU dialog box no longer let's you set this
    information.  Instead, the Options/CPU dialog displays the detected
    CPU type and speed.  This new feature helps prevent incorrect settings
    when users upgrade or try several overclocking speeds.  If the new
    algorithm fails, you can overide the settings as described in undoc.txt.
5)  Benchmark now writes the program version, timing methodology, cpu type
    and speed, L1 and L2 cache information to results.txt.  It will refuse to
    benchmark if rdtsctiming is 10.

New features in Version 21.4 of prime95.exe
-------------------------------------------

1)  Exiting the Torture Test now prints out how long it ran.
2)  P4 error checking was relaxed slightly to reduce false alarms.

New features in Version 21.3 of prime95.exe
-------------------------------------------

1)  The program will now skip the P-1 factoring stage if another user has
    already performed this step.
2)  The Advanced/Quit GIMPS menu choice now lets you quit after current
    work completes or quit immediately.
3)  A bug was fixed in the error recovery code.  After getting a "Disregard
    last error" message, the user was treated to a new error on every
    iteration.  The end result was incorrect.  The bug only affected the